The invention relates to a computer imaging system and method for detecting new skin lesions and significant changes in existing skin lesions.
It is well known that rapid changes in the size of a mole or skin lesion may indicate the onset of precancerous or cancerous tissue growth and that early detection of such changes usually results in a much better prognosis for the patient, especially if the lesion is a melanoma. In the case of a melanoma, a delay of a month or two in detection may make the difference between successful treatment or death of the patient. Unfortunately, most people have difficulty detecting early changes in the size of a skin lesion because initial changes in size are slow and subtle. Furthermore, a physician observing a lesion usually does not have prior “baseline” or reference information on the lesion from which to judge the amount or rate of its growth.
Because there is no generally effective treatment for metastatic melanoma, even small cancers often prove fatal if not detected early. This is unfortunate, because few cancers provide a greater opportunity for early discovery and removal than melanoma, because cutaneous melanoma (1) is located on the skin surface where it is readily observed, and (2) usually undergoes an easily observable “radial growth” phase prior to metastasis. The radial growth stage of a cancerous skin lesion therefore provides a window of opportunity during which the lesion can be detected and removed before metastasis, with a high probability of a complete cure.
The closest prior art is believed to include our publication “Video Comparator System for Early Detection of Cutaneous Malignant Melanoma”, SPIE vol. 1653/Image Capture Formatting, and Display (1992). Various difficulties were encountered in providing a practical implementation of the basic technique described in that article using a microcomputer-based video imaging system for storing an image archive of historical reference images for each patient, registering and scaling current images with baseline images, and using an “alternating image comparison display” comparison of the image pairs in a manner that is readily acceptable by and useable by patients. Those difficulties led to our development of the invention disclosed in our U.S. Pat. No. 6,427,022 “Image Comparator System and Method for Detecting Changes in Skin Lesions”, filed Nov. 10, 1988 and issued Jul. 30, 2002, and incorporated herein by reference. In the system disclosed in the '022 patent, two buffers were included that allowed a previously stored digitized baseline image of a portion of a subject's body and a corresponding current “live” image to be alternately displayed so that good registration/alignment between the baseline image and the current image could be achieved by manipulating the video camera being used. However, we learned that in a clinical setting the spatial resolution of the images acquired in this manner was poor. In order to achieve the resolution required to adequately resolve small moles and lesions, it was found to be necessary to make a large number of small-format digital images which had to be very precisely matched and/or aligned using the alternate display technique. But that was found to be impractical in a clinical setting because the procedure is very labor-intensive and time-consuming. Later we tried using the same basic technique to digitize segments of the images on high-resolution film, which allowed some of the labor-intensive part of the process to be performed in a laboratory instead of in a clinical setting.
However, it clearly is highly desirable to be able to perform the technique of identifying significant new lesions or changes in existing lesions without the necessity of a labor-intensive, time-consuming “intermediate service” operation being included in the process.
There clearly is a great need, which up to now has not been fulfilled, for an inexpensive, workable, accurate system and convenient technique by which ordinary people with access to a digital camera can conveniently monitor the growth of skin lesions on their entire bodies in the privacy of their own homes and reliably determine which lesions have grown significantly and which are new and submit such information to a dermatologist who can then expertly observe new lesions and lesions which have significantly changed since a prior examination.
There is an unmet need for an inexpensive, workable, accurate, convenient system for providing an objective comparison of many or all lesions on a subject's body irrespective of whether the lesions are “suspect” or likely to be cancerous.
There is an unmet need for an inexpensive, workable, accurate, convenient system for providing an objective comparison of many or all lesions on a subject's body while avoiding difficulties inherent in the use of photographic film.
There is an unmet need for an inexpensive, workable, accurate, convenient system for aligning and comparing images of current skin lesions with images of baseline skin lesions and thereby improving the likelihood of detecting significant changes in skin lesions.
There is an unmet need for an inexpensive, workable, accurate, convenient system that makes it easy for untrained subjects to align current lesion images in the field of view of an ordinary digital camera with corresponding baseline lesion images.